Ergothioneine (EGT) is a rare natural chiral amino acid, and as an important physiologically active substance in the living body, ergothioneine has many biological functions such as antioxidation, preventing ultraviolet radiation damages, regulating oxidation-reduction reactions in the cells, chelating divalent metal ions, participating in energy regulation in the cells and so on, and thus ergothioneine is a multifunctional cellular physiological protector (Qi Liu, Wen-xia Jiang, Ping Yang, Tao Zhou, L-Ergothioneine—A multifunctional physiological cytoprotector [J]. Nat. Pro. Res. Dev., 2013, 25 (Suppl.): 160-164.). Ergothioneine is a product generally recognized as safe (GRAS) with stable property, which has important application values and broad application prospects in the industries of pharmaceuticals, biomedicine, food, health food, food additives, cosmetics, etc.
Since the production cost of ergothioneine is high at present, the application thereof is limited. As compared with a chemical synthesis method and a natural biological extraction method, producing ergothioneine by submerged fermentation of edible fungus may improve the accumulation of ergothioneine, achieve large-scale efficient production, reduce production costs, and have the advantages of product safety, etc. by establishing a control strategy for a high density fermentation process, and thus is the development direction of synthetizing ergothioneine (Qi Liu, Wei-ya Zhang, Wen-xia Jiang, Bao-liang Mei, Tao Zhou, Research progress of ergothioneine biosynthesis technology [C]. Symposium of international summit forum on amino acid industry development in 2013. 2013: 22-27.).
Pramvadee Tepwong et al. in Japan produced ergothioneine by submerged fermentation of Lentinula edodes mycelia, and the yield of ergothioneine was 23.6 mg/L in the fermentation broth after fifteen days fermentation. (Pramvadee Tepwong, Anupam Giri, Fumito Sasaki. Microbial enhancement of ergothioneine by submerged cultivation of edible mushroom mycelia and its application as an antioxidative compound [J]. Food Chemistry, 2012, 131: 247-258.); Wi Young Lee et al. in Korea synthesized ergothioneine by fermentation of Ganoderma neo-japonicum mycelia, and the content of ergothioneine in the fermentation broth reached 57.5 mg/L at the end of fermentation (Wi Young Lee, Eung-Jun Park, Jin Kwon Ahn. Supplementation of methionine enhanced the ergothioneine accumulation in the Ganoderma neo-japonicum mycelia [J]. Appl Biochem Biotechnol, 2009, 158: 213-221.); Ling-yi Huang and Chih-hung Liang in Taiwan subjected Pleurotus eryngii mycelia to liquid fermentation and culture, and after the culture, the yield of ergothioneine in the fermentation broth reached 62.2 mg/L (Ling-yi Huang. Submerged cultivation and physiological activities of Pleurotus eryngii mycelia with a high ergothioneine content [D]. Taiwan: National Chung Hsing University, 2010) and 60.4 mg/L (Chih-Hung Liang, Ling-Yi Huang, Kung-Jui Ho, et al. Submerged cultivation of mycelium with high ergothioneine content from the culinary-medicinal king oyster mushroom Pleurotus eryngii (higher basidiomycetes) and its composition [J]. International Journal of Medicinal Mushrooms, 2013, 15(2): 153-164.), respectively; Wen-xia Jiang et al. produced ergothioneine by fermentation of Pleurotus ostreatus mycelia, and through the optimization of fermentation medium and fermentation control process, the content of ergothioneine in the fermentation broth reached 135.7 mg/L (Wen-xia Jiang, Qi Liu, Tao Zhou. The strain for producing ergothioneine and method for producing ergothioneine [P]. CN 201210392417.8).